Friends Light Up the Brain

Close friends activate "social" areas of your brain more than strangers do, even if you have more in common with the strangers.

According to a new study from Harvard University, thinking about a close friend activates certain areas of the brain more strongly than thinking about a stranger, even if the stranger has more in common with you. The research is illuminating since it contrasts what researchers had previously thought about how the brain responds to close friends vs. "similar" strangers.

Social information may actually be intimately connected to personally significant information. That’s why making social "judgments" activates these brain systems so strongly.

In the new study, led by graduate student Fenna Krienen, the researchers had participants answer questions about their close friends as well as "strangers". The strangers were fictitious and made up by the researchers: they were constructed to be either similar or different from the participants, but not stereotypically so. For example, Krienen and her team write "if a participant is a self-described liberal Democrat and indicates that his similar friend is a moderate Democrat and his dissimilar friend is a moderate Republican, the similar and dissimilar strangers would also be a moderate Democrat and Republican, respectively." The participants were asked to judge statements about their friends and strangers, relative to their own beliefs.

The participants’ brains were scanned while they were making these judgments so that the researchers could see exactly how their brains responded as they thought about both friends and strangers who had much or little in common with the participant.

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The researchers found that areas of the brain important in processing social information were more active when participants thought about their friends than when they thought about strangers, even when the strangers’ beliefs were more in line with their own.

What does this say about the way the brain processes social information? Krienen and her team say that "one interpretation of ‘social’ tasks such as thinking about close others is that they rely on systems optimized to process information perceived to be significant to the individual". In other words, social information may actually be intimately connected to personally significant information. That’s why making social "judgments" activates these brain systems so strongly. As the researchers say, humans are deeply social creatures, and large portions of the brain are devoted to processing this kind of information. So let your brain do what it does well, and enjoy the closeness of your friends and loved ones.

The study was published in the October 13, 2010 issue of the Journal of Neuroscience.